ethyl aniline are widely used promoters for this system. A multifunctional monomer known
as trimethylol propane trimethacrylate is also used in combination with the methyl meth-
acrylate in 5:95 ratio to increase the rate of polymerization of the acrylic system. The pro-
moter and initiator content can be adjusted to control the setting time at any given tempera-
ture, thus making this system usable for cold-weather patching at low temperatures.
Methacrylate systems (Degussa Corporation, Ridgefield, New Jersey) are able to cure fully
in one to two hours at temperatures down to 29C (20F) and are generally utilized for
resurfacing, patching, and joint rehabilitation.
This system has been successfully lab-tested at temperatures between 9.4 to 6.7C (15
to 20F). However, the performance of commercial systems at low temperatures needs
further investigation since no successful outside patching at low temperatures has been
reported. Also, the requirement for dry aggregates and patch surfaces and strong odor are
several handicaps of this system.
HYBRID INORGANIC-ORGANIC BINDERS
Two kinds of materials, polymer- (latex) modified and polymer-infiltrated binders, fall
under this category. In recent years, polymer latex-modified mortars and concrete have
been widely used as construction materials because of their improved properties of high
strength, extensibility, adhesion, waterproofing, and durability. Three kinds of latexes have
been used for this purpose. The most common latex has been the styrene-butadiene copoly-
mer. Other latexes, such as vinylidene chloride-vinyl chloride copolymer and polyacrylic
esters, have also been used for mortar applications. Generally, latex-modified concrete will
provide higher strength after air curing compared to water curing because of the film-form-
ing ability of dried latex particles. However, no use of such binders at low temperatures was
found in the literature. One problem with these latex suspensions is that they should not
freeze, because the suspension property would be lost and the latex particles would not be
uniformly distributed throughout the matrix.
The polymer-infiltrated concrete has been primarily used for restoration purposes. The
acrylic polymeric systems described previously under the organic binders can be used for
this purpose. The low viscosity of acrylic monomers helps the infiltration of the monomer
within the matrix. Because acrylics can be used at low temperatures, repair and restoration
of damaged concrete can be performed applying this technique.